linux/arch/ia64
Brent Casavant e08e6c5213 [IA64] hooks to wait for mmio writes to drain when migrating processes
On SN2, MMIO writes which are issued from separate processors are not
guaranteed to arrive in any particular order at the IO hardware.  When
performing such writes from the kernel this is not a problem, as a
kernel thread will not migrate to another CPU during execution, and
mmiowb() calls can guarantee write ordering when control of the IO
resource is allowed to move between threads.

However, when MMIO writes can be performed from user space (e.g. DRM)
there are no such guarantees and mechanisms, as the process may
context-switch at any time, and may migrate to a different CPU as part
of the switch.  For such programs/hardware to operate correctly, it is
required that the MMIO writes from the old CPU be accepted by the IO
hardware before subsequent writes from the new CPU can be issued.

The following patch implements this behavior on SN2 by waiting for a
Shub register to indicate that these writes have been accepted.  This
is placed in the context switch-in path, and only performs the wait
when the newly scheduled task changes CPUs.

Signed-off-by: Prarit Bhargava <prarit@sgi.com>
Signed-off-by: Brent Casavant <bcasavan@sgi.com>
2006-01-26 15:55:52 -08:00
..
configs [PATCH] e1000: Added disable packet split capability 2006-01-18 16:17:57 -05:00
dig Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
hp [PATCH] remove unused tmp_buf_sem's 2006-01-14 10:41:42 -08:00
ia32 [IA64] sem2mutex: arch/ia64/ia32/sys_ia32.c 2006-01-19 11:17:33 -08:00
kernel [IA64] eliminate softlockup warning 2006-01-19 11:18:25 -08:00
lib Merge branch 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux-2.6 2005-10-28 21:09:26 -07:00
mm [IA64] Simple memory hot-add for ia64. 2006-01-16 12:06:55 -08:00
oprofile [PATCH] remove gcc-2 checks 2006-01-08 20:14:02 -08:00
pci [IA64] Stop multiple pci_claim_resource() call for the same resource 2006-01-16 15:30:10 -08:00
scripts Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
sn [IA64] hooks to wait for mmio writes to drain when migrating processes 2006-01-26 15:55:52 -08:00
defconfig [PATCH] e1000: Added disable packet split capability 2006-01-18 16:17:57 -05:00
install.sh Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00
Kconfig [PATCH] Fix Kconfig of DMA32 for ia64 2005-12-12 08:57:45 -08:00
Kconfig.debug [PATCH] Move Kprobes and Oprofile to "Instrumentation Support" menu 2005-11-07 07:53:35 -08:00
Makefile [PATCH] remove gcc-2 checks 2006-01-08 20:14:02 -08:00
module.lds Linux-2.6.12-rc2 2005-04-16 15:20:36 -07:00